First, the principle of brush motor
To clarify this issue, you should have a rough understanding of how the brush motor works. Next, a three-electrode, two-pole inner rotor brushed motor was used as a demonstration.
Second, the working principle of brushless motor
First of all, the brushless motor is not a DC motor. Although the model is powered by a DC battery, it is converted to three polarities by three-phase alternating current after brushless ESC. As can be seen from the figure below, the brushless motor has no carbon brush. In contrast to the brush, the magnet of the brushless motor becomes the rotor~
Third, the name of the brushless motor
Compared with the brush motor, the name of the brushless motor is well understood. Generally, it consists of four numbers, such as a 2040 brushless motor. This figure only represents the external dimensions of the motor. 2040 represents a motor with a diameter of 20 mm and a length of 40 mm. Similarly, the 3650 brushless motor indicates that the motor has a diameter of 36 mm and a length of 50 mm.
In fact, the size of the 370 brush motor is the same as that of the 2530 brushless motor. The size of the 540 motor is the same as that of the 3650 brushless motor.
Fourth, the characteristics of brushless motor
1. There is no carbon brush. In theory, the rotor does not need to have a link with the outside world.
2. During the running process, the speed of the brushless motor is determined by the frequency of the alternating current, so the higher the frequency, the faster the brushless motor can turn.
3. The speed of the brushless motor is set strictly according to the KV value. 1000KV means that the speed of each Ford motor is 1000 rpm. Therefore, when the voltage is 5V, the 1000kv brushless motor rotates at 5000rpm.
So why do we want to sense this stuff? To clarify this problem, we must start with a shortcoming of feeling no brush. Just said that the speed of the brushless motor is determined by the frequency of the alternating current, then the ESC should try to figure out the current motor speed and the current state of the motor. In fact, this is very easy for a motor that is already running normally, but it is more troublesome for a motor that has just started or is running very slowly (it is difficult to accurately measure the state of the motor speed), so there is no feeling. The brush motor will not be linear or even tremble at low speeds, and the starting torque will not be stronger than the same level brush motor.
However, it has been found that the Hall effect of any brushless motor is obvious, so it is easy to know the operating state of the high-speed or low-speed motor through the Hall effect ESC, thus solving the problemless brushless motor. The fault of the motor! But for the time being, Hall sensors are not cheap goods, so the price of brushless motors and ESCs is much more expensive than non-sense.
Seven, common models with brush, no sense of no brush, sense of brushless motor comparison
Brushed motor, no feeling, no brush, no brush, no brush
Conversion efficiency: low high
Motor output power: low high
Starting torque: good, generally good
Medium and high speed torque: generally good
Low speed linearity: better generally good
Medium and high speed linearity: Good Good
The highest speed (generally 540 motor): common 20,000 common 50,000 common 50,000
Easy to wear: Easy to wear, not easy to wear, not easy to wear
Motor price (540) Mid-range 100RMB Minimum 120RMB Minimum 200RMB
ESC price (540) Mid-range average 120 or so Minimum 200RMB Minimum 300RMBxx